This invention relates to a novel process of bonding particles of various materials to each other and/or to a supporting surface or member, and to articles produced according to the process.
At various times in the history of making abrasive material commonly referred to as xe2x80x9csandpaperxe2x80x9d by the general public, adhesives used to adhere the abrasive grit to a backing sheet material have gone from using natural glue type materials to various kinds of artificial resins and epoxy materials. Typically, most adhesive materials used today require the liquification of an adhesive that is usually applied to a backing sheet. This is usually done by employing various environmentally-unfriendly solvents. These solvents are not only messy to handle, but are at times unsafe for the personnel using them. In addition, state and federal laws frequently require that the solvents not be released into the atmosphere, thus requiring that a manufacturing process further include expensive equipment for preventing such release and, in some instances, reclaiming the captured substance. Certain hot melt adhesive processes have also been considered to eliminate solvent usage, but to my knowledge, are not in common use.
Conventional manufacture of abrasive sheet material requires expensive equipment occupying considerable space and auxiliary equipment for handling solvent flashing. The advantages of being able to provide low cost, low volume manufacture of abrasive sheet material in a relatively safe environment is apparent.
The invention relates to an environmentally-safe heat-reactive curable melt adhesive in fine crystalline powder form, its mixture with any of a large variety of compatible particulate materials and heating the mixture to a predetermined temperature for a predetermined time during which the powder liquifies and cross links. The preliminary mixture can be accomplished by gentle tumbling, and in the process, the powder crystals cling to the particles. Upon subsequent cooling, the powder adhesive bonds the particles to each other and/or to each other and to a supporting member or surface. Application of pressure at the time of heating is particularly useful where the end product has some thickness.